Method for connection establishment in a radio system relaying packet-switched traffic

ABSTRACT

The invention relates to a method for connection establishment and a radio system relaying packet traffic. A terminal informs the system that it wishes to transmit data. The network part receives the message and allocates default radio resources and informs the allocated resources to the terminal. The terminal sends a first control message to inform the terminal&#39;s radio path characteristics. According to the solution of the invention, when allocating the default amount of radio resources to the terminal, the network part is arranged to reserve one or more radio blocks for the terminal&#39;s control messages. When the terminal sends the network part information about its radio path characteristics, it is arranged to inform in the message if there are additional characteristics. In that case, the terminal sends a second control message including information about its radio path characteristics.

This application is a continuation of U.S. patent application Ser. No.10/021,297, filed Dec. 19, 2001, which is a continuation ofInternational Application PCT/FI00/00551, filed Jun. 20, 2000, whichrelies for priority on Finnish Application Nos. 991412, filed Jun. 21,1999 and 19992529, filed Nov. 25, 1999, the contents of all of which areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The invention relates to a radio system relaying packet-switched trafficand to a method for connection establishment in a radio system relayingpacket-switched traffic. The invention relates particularly to a radiosystem where terminals have various radio path characteristics.

BACKGROUND OF THE INVENTION

A significant shortcoming in current radio systems and in those that arebeing developed is the limited amount of radio resources available. Thenumber of radio frequencies is restricted and they are distributed amongvarious systems and operators. Numerous different solutions have beencreated to solve this problem.

Previously developed radio systems meant for public use are based oncircuit-switched technology. In systems implemented according to thistechnology, a specific channel is reserved for the connection betweenthe devices involved, the connection being available to the devices forthe entire duration of the connection, irrespective of whether there istraffic on the channel all the time or not. This solution has beensufficient for systems relaying primarily speech. However, withincreasing telecommunications needs, transmission connections are usedfor transmitting data. The traffic relayed on data connections is oftenhighly bursty, i.e., at times data is transferred in large amounts and alot of transmission capacity is needed on the channel, whereasoccasionally the traffic load on the channel is low. From the point ofview of capacity deployment, packet-switched transmissions are anextremely good solution for these connections. In packet-switchedconnections, the channel is not allocated to the terminals for theentire duration of the connection, but the channel is only allocatedwhen data needs to be transferred. Consequently, diverse radio systemsemploying packet-switched service have been developed, at least some ofthe connections between the terminals being established using a packetprotocol. Among these systems are GPRS (General Packet Radio System) andits enhanced version EGPRS (Enhanced General Packet Radio System).

Since various data services are available and they have differing datatransmission needs, many systems include the possibility to establishconnections of varying capacity. Moreover, many systems involve diverseterminals which may be provided with highly varying data transmissionproperties and capability to deploy the resources of the system. Forexample, different equipment and data transfer capacity is needed fortransferring speech, written communications or video. In addition, theremay be devices that can only use specific frequency ranges and othersthat can utilize all the frequencies reserved for the network.Consequently, when a radio connection is to be established, the systemshould know the type of the terminal that needs the connection and thedata transmission capacity. There are also networks that may havedifferent packet system protocols available, such as the GPRS and EGPRS,and, depending on its characteristics, the terminal can use one or theother.

In prior art solutions a terminal that needs to transmit data in packetformat contacts the network and informs that it wishes to establish aconnection and, at the same time, it informs what kind of a terminal itis, i.e., the radio path characteristics it has. These characteristicsinclude for example the frequencies the device needs for communication,and the transfer modes of different capacities that the terminal canutilize. A prior art signalling for connection establishment isillustrated in FIG. 1. The Figure shows the essential parts of messagessent by different devices. The messages sent by the network part aremarked with DL (downlink). A terminal sends a CR (Channel Request) 100to the network part of the system. The network part allocates one radioblock to the terminal and responds by sending the terminal an IA(Immediate Assignment) 102. The terminal uses the allocated radio blockto send a PRR (Packet Resource Request) 104. This request comprisesinformation about the terminal's radio path characteristics. The networkpart allocates one or more channels to the terminal and responds bysending a new response 106 where the reserved channels are informed tothe terminal. The terminal then starts to send data 108. In the exampleof FIG. 1, the terminal uses three parallel 110-114 channels.

One of the drawbacks of the above method is that it is not possible toknow whether the terminal needs GPRS (General Packet Radio System) orEGPRS (Enhanced General Packet Radio System) resources. Another problemis that one allocated block is sufficient for sending one controlmessage, but one control message is not always enough for relaying theradio characteristics of the terminal. Consequently, a terminal havingdiversified characteristics does not necessarily receive appropriateresources.

The signalling that takes place before data transmission is a multi-stepprocess, i.e., it comprises a plural number of steps depending on theamount of data to be transferred and the amount resources available.When GPRS is used, the signalling can take place either on a PCCCH(Packet Common Control Channel) or a CCCH (Common Control Channel), butwith EGPRS only PCCCH can provide efficient signalling. This causesdelay in the transmission of the signal and yet the data transmission isnot necessarily carried out in an optimal way due to insufficientsignalling capacity.

BRIEF DESCRIPTION OF THE INVENTION

It is therefore an object of the invention to provide a method and aradio system allowing connections between a terminal and a network to beestablished smoothly and effectively. This is achieved with a connectionestablishment method of the invention employed in a radio systemrelaying packet service, in which method the terminal informs the systemnetwork part that it wishes to send data to the network part; thenetwork part receives the message and allocates a default amount ofradio resources to the terminal; the network part informs the allocatedresources to the terminal; the terminal sends a first control message toinform the network part about the terminal's radio path characteristics.According to the method of the invention, when the network partallocates the default amount of radio resources to the terminal, itreserves one or more radio blocks for the terminal's control messages,and when the terminal sends information about its radio pathcharacteristics to the network part, the terminal also informs in themessage if there are additional characteristics, and, in that case, theterminal sends a second control message comprising information about theterminal's radio path characteristics.

The invention also relates to a radio system relaying packet-switchedtraffic, in which system a terminal is arranged to inform the systemnetwork part that it wishes to send data to the network part; a networkpart is arranged to receive the message and to allocate a default amountof radio resources to the terminal; the network part is arranged toinform the allocated resources to the terminal; the terminal is arrangedto send a first control message to inform the terminal's radio pathcharacteristics to the network part. According to the system of theinvention, when the network part allocates the default number of radioresources to the terminal, the network part is arranged to reserve oneor more radio blocks for the terminal's control messages, and when theterminal informs the network part about its radio path characteristics,the terminal is arranged to inform in the message if there areadditional characteristics, and, in that case, the terminal is thenarranged to send a second control message comprising information aboutthe terminal's radio path characteristics.

According to a preferred embodiment of the invention, after havingreceived the information about the allocated resources from the networkpart, the terminal starts to send data to the network part, immediatelyafter it has sent the requested control messages using the allocatedradio resources.

In another preferred embodiment of the invention, the terminal isallocated a predetermined number of channels immediately after the firstchannel request. Data transmission can then begin, and, when it begins,the terminal's characteristics are signalled to the network. Accordingto another preferred embodiment of the invention, the network part isarranged to allocate radio resources to the terminal in accordance withthe terminal's characteristics, which allows the number of channels tobe increased, when necessary.

According to a further preferred embodiment of the invention, the firstcontrol message comprises information about the terminal's radio pathcharacteristics preferably with regard to the frequency band the networkpart first inquired about in the control message it sent. The secondcontrol message sent by the terminal informs the terminal's radio pathcharacteristics preferably with regard to all frequency bands availablein the network. If there are so many radio path characteristics thatthey cannot be included even in this message, then new control messagesare sent until all the radio path characteristics have been informedwithin the scope of the allocated resources.

The method and arrangement of the invention provide several advantages.Data transmission can be rapidly initiated and channel deploymentbecomes more efficient. On the other hand, the network is formed moreeffectively than before about the terminal's characteristics, whichallows an appropriate number of channels to be allocated for aconnection. Furthermore, the terminal can be used for sending moreinformation to the network than before, i.e., information from allfrequency bands supported by the network and the terminal. Previouslythe information has been limited to one frequency band alone.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail inconnection with preferred embodiments and with reference to theaccompanying drawings, in which

FIG. 1 illustrates the prior art solution described above;

FIG. 2 illustrates an example of a telecommunications system in whichthe invention can be applied;

FIG. 3 illustrates the structure of another mobile communications systemused as an example;

FIG. 4 illustrates in greater detail the structure of a mobilecommunications system used as an example;

FIG. 5 illustrates an example of the structure of a transceiveraccording to a system of the invention;

FIGS. 6 a and 6 b illustrate a method of the invention; and

FIGS. 7 a and 7 b illustrate examples of a solution of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention can be used in various radio systems relayingpacket service in which terminals are provided with diverse radio pathcharacteristics. The multiple access method employed in the system isnot significant as such. For example, multiple access methods such asCDMA, WCDMA and TDMA can be used. Also, the system can support bothcircuit- and packet-switched connections. FIG. 2 illustrates a digitaldata transmission system in which the solution of the invention can beapplied. It is a part of a cellular radio system comprising a basestation 200 which has a bi-directional connection 202-206 to subscriberterminals 208-212. The base station is further connected to a basestation controller 214 which relays the terminals' connections furtherto other parts of the network. In the simplified example shown in FIG. 2some of the connections can be circuit-switched and otherspacket-switched connections.

With reference to FIG. 3, the structure of a mobile communicationssystem used as an example will be described. The main parts of themobile communications system are core network CN, above-ground radioaccess network BSS and subscriber station MS. In this example theinterface between the CN and the BSS is called Gb, and the air interfacebetween the BSS and the MS is called Um.

The radio access network consists of base station subsystems BSS. EachBSS comprises a base station controller BSC and one or more basetransceiver stations BTS. The interface between the base stationcontroller BSC and the base station BTS has not been standardized. Thecoverage area of the base station, i.e., a cell, is indicated with 3 Cin the Figure.

The description given in FIG. 3 is rather abstract and therefore it isclarified with a more detailed example of a cellular radio system givenin FIG. 4. FIG. 4 only comprises the most essential blocks, but a personskilled in the art will find it apparent that a conventional cellularradio network also comprises other functions and structures which neednot be explained in greater detail in this context. It is also pointedout that FIG. 4 only shows one exemplary structure. The details ofsystems according to the invention may vary from those shown in FIG. 4,but such differences are not significant to the invention.

A cellular radio network typically comprises a fixed networkinfrastructure, i.e., a network part 400, and subscriber terminals 402,which may be fixedly located, vehicle-mounted or portable terminals. Thenetwork part 400 comprises base stations 404. A plural number of basestations 404 are, in turn, controlled in a centralized manner by a basestation controller 406 communicating with them. The base station 404comprises transceivers 408 and a multiplexer 412.

The base station 404 further comprises a control unit 410 which controlsthe operation of the transceivers 408 and the multiplexer 412. Themultiplexer 412 arranges the traffic and control channels used byseveral transceivers 408 to a single transmission connection 414, whichforms an interface hub.

The transceivers 408 of the base station 404 are connected to an antennaunit 418 which is used for implementing a bi-directional radioconnection 416 to the subscriber terminal 402. The structure of theframes to be transmitted in the bi-directional radio connection 416 isdefined separately in each system, the connection being referred to asan air interface Um.

The base station controller 406 comprises a group switching field 420and a control unit 422. The group switching field 420 is used forconnecting speech and data and for combining signalling circuits. Thebase station 404 and the radio network controller 406 form a radionetwork subsystem 432 which further comprises a transcoder 424. Thetranscoder 424 is usually located as close to a mobile servicesswitching centre 428 as possible, because speech can then be transferredin a cellular radio network form between the transcoder 424 and the basestation controller 406, which saves transmission capacity.

The transcoder 424 converts different digital speech coding forms usedbetween a public switched telephone network and a radio network to makethem compatible, for instance from a fixed network form to anothercellular radio network form, and vice versa. The control unit 422performs call control, mobility management, collection of statisticaldata and signalling.

FIG. 4 further shows the mobile services switching centre 428 and agateway mobile services switching centre 430 which controls theconnections between the mobile communications system and the outsideworld, in this case to a public switched telephone network 436.

As is seen in FIG. 4, the group switching field 420 can be used forswitching to both the public switched telephone network PSTN 436,through the mobile services switching centre 428, and to a packettransmission network 442.

The connection between the packet transmission network 442 and the groupswitching field 420 is established by a SGSN (Serving GPRS Support Node)440. The function of the support node 440 is to transfer packets betweenthe base station subsystem and a GGSN (Gateway GPRS Support Node) 444,and to keep record of the subscriber terminal's 402 location within itsarea.

The gateway node 444 connects a public packet transmission network 446with the packet transmission network 442. An Internet protocol or anX.25 protocol can be used at the interface. The gateway node 444encapsulates the inner structure of the packet transmission network 442to conceal it from the public packet transmission network 446, thereforethe public packet transmission network 446 sees the packet transmissionnetwork 442 as a subnetwork, and the public packet transmission networkcan address packets to and receive them from the subscriber terminal 402located in the network.

The packet transmission network 442 is typically a private networkemploying an Internet protocol and carrying signalling and tunneled userdata. Below the Internet protocol layer, both the architecture andprotocols of the network structure 442 may vary according to operator.

The public packet transmission network 446 may be for example the globalInternet network, to which a terminal 448, such as a server computer,communicating with the network wishes to transfer packets addressed tothe subscriber terminal 402.

At the air interface 416 packet transmission typically takes place intime slots not allocated for circuit-switched transmission. Packettransmission capacity is allocated dynamically, i.e., when a datatransmission request is received, any free channel may be allocated forpacket transmission. The arrangement is flexible, circuit-switchedconnections having priority over packet transmission connections. Whennecessary, a circuit-switched connection cancels a packet-switchedconnection, i.e., a time slot engaged in packet transmission isallocated to a circuit-switched connection. This is possible becausepacket transmission tolerates such interruptions well: the transmissionsimply continues in another time slot allocated to the connection.Another possibility to implement the arrangement is thatcircuit-switched transmissions are not given any absolute priority, butboth circuit-switched and packet-switched transmission requests areserved in their order of arrival. Such arrangements are not, however,significant to the present invention.

FIG. 5 describes the structure of a transceiver 408 in greater detail. Areceiver 500 comprises a filter blocking frequencies outside the desiredfrequency band. A signal is then converted to an intermediate frequency,or directly to baseband, in which form the signal is sampled andquantized in an analog-to-digital converter 502. An equalizer 504compensates for disturbance, caused for example by multi-pathpropagation. A demodulator 506 extracts a bit stream from the equalizedsignal for transmission to a demultiplexer 508. The demultiplexer 508separates the bit stream from the different time slots into the specificlogical channels. A channel codec 516 decodes the bit stream of thedifferent logical channels, i.e., it decides whether the bit stream issignalling data, which is to be transmitted to a control unit 514, orspeech, which is to be transmitted 540 to a transcodec 424 of the basestation controller 406. The channel codec 516 also performs errorcorrection. The control unit 514 carries out internal control functionsby controlling the separate units. A burst former 528 adds a trainingsequence and a tail to the data arriving from the channel codec 516. Themultiplexer 526 assigns a time slot for each burst. The modulator 524modulates the digital signals onto a radio frequency carrier. This is ananalog function and therefore a digital-to-analog converter 522 isneeded for performing it. A transmitter 520 comprises a filter forrestricting the bandwidth. In addition, the transmitter 520 controls theoutput power of the transmission. A synthesizer 512 arranges thenecessary frequencies for the different units. The synthesizer 512comprises a clock which may be controlled either locally or centrally,from somewhere else, for example from the base station controller 506.The synthesizer 512 generates the necessary frequencies for example byusing a voltage-controlled oscillator.

As shown in FIG. 5, the transceiver structure can be further dividedinto radio frequency parts 530 and digital signal processing includingsoftware 532. The radio frequency parts 530 comprise the receiver 500,transmitter 520 and synthesizer 512. The digital signal processor withthe software 532 comprises the equalizer 504, demodulator 506,demultiplexer 508, channel codec 516, control unit 514, burst former528, multiplexer 526 and modulator 524. To convert an analog radiosignal to a digital signal, the analog-to-digital converter 502 isneeded and, correspondingly, to convert a digital signal to an analogone, the digital-to-analog converter 522 is needed.

The structure of the subscriber terminal 402 can also be described usingthe description of the transceiver 408 in FIG. 5. The structural partsof the subscriber terminal 402 are operationally the same as those ofthe transceiver 408. In addition to the above described structure, thesubscriber terminal may comprise a duplex filter between an antenna 418and the receiver 500 and the transmitter 520, user interface parts and aspeech codec. The speech codec is connected to the channel codec 516over a bus 540. The functions of the invention can be provided in theterminal typically by software incorporating all the necessary commandsand placed at the disposal of the terminal's control unit.

In the network part the functions of the invention can be advantageouslyimplemented by software. The software comprising the necessary functioncommands can be placed at the base station, the radio network controlleror in the support node SGSN in a unit that processes RLC-MAC protocolmessages. The RLC-MAC messages relate to the protocols used in radionetworks, the protocols being typically formed in accordance with theOSI (Open Systems Interconnection) model of the ISO (InternationalStandardization Organization). In the RLC/MAC sublayer (Radio LinkControl/Medium Access Control), the RLC part is responsible forsegmenting and collecting the data to be transmitted. In addition, theRLC part conceals quality fluctuations in the radio connection of thephysical layer from the upper layers. The MAC part allocates trafficchannels to and releases them from radio bearers.

Let us now examine the operation of the inventive solution withreference to the flow diagram of FIG. 6 a in a situation where theterminal needs to send information in packet format. A system known asthe EGPRS (Enhanced General Packet Radio System) will be used as anexample in this specific case, the invention not being, however,restricted to it. In the example, a TBF (Temporary Block Flow)connection is established between two devices for data transmission.

In the first step, the terminal sends a Channel Request CR 600 to thenetwork part. The terminal uses a specific training sequence to indicateto the base station that the channel request in question is specificallyof the EGPRS-type. If the request were of a GPRS-type, another kind oftraining sequence would be used. After having received the message, thenetwork part allocates to the terminal a channel on the radio path fordata transmission (step 602) and informs the terminal about theallocated resources by sending an AGCHPUA (Access Grant Channel PacketUplink Assignment) message 604. The message may also compriseinformation about the frequencies used in the cell and about thefrequency band with regard to which the base station first wishes toknow the terminal's characteristics. Moreover, the network partallocates in step 606 one or more radio blocks to the terminal forcontrol messages.

The terminal then sends the network part a PRR (Packet Resource Request)message in a first control block (step 608). The message comprisesinformation about the terminal's radio path characteristics, preferablyrelating to the frequency band that was requested in the first AGCHPUAmessage. The PRR message further comprises information stating that theterminal has also other characteristics than those mentioned in themessage.

In the next control block in step 610 the terminal sends a secondmessage ARAC (Additional Radio Access Capability) in which theterminal's radio path characteristics are stated preferably with regardto all other frequency bands available in the network. The terminalreceives this information in step 604. If the terminal has morecharacteristics than a single ARAC message can accommodate, several ARACmessages are sent within the resources allocated. The sending of theactual data does not start until the control messages have been sent. Inthe next phase 612 the terminal starts to send data to the network part,using the radio resources allocated to it.

If necessary, in step 614 the network part re-allocates new resources tothe terminal on the basis of the information it has received.

If the terminal does not support other frequency bands than thosealready mentioned in the first control message, then a second controlmessage is not needed, but data can be sent instead. The network part isable to distinguish data from control messages on the basis of themessage headers.

The PRR and the ARAC should both be sent within N blocks from thestarting of the data transmission, N being preferably 40. If thetransmission is shorter than N blocks, then neither of the controlmessages is sent.

In a preferred embodiment of the invention, the network part uses step604, i.e., a message PUA (Packet Uplink Assignment) to ask forinformation about the frequency ranges and radio path characteristicsthat the terminal supports. In another preferred embodiment of theinvention the network part uses a common signalling channel (also knownas a broadcast channel) to inform all terminals located within its arethat it wishes the terminals to broadcast information about thefrequency ranges and radio path characteristics they support. Thecontrol channel can be for example a Broadcast (BCCH) or PacketBroadcast (PBCCH) channel.

Let us then examine the operation of the inventive solution withreference to a flow diagram shown in FIG. 6 b in a situation where atwo-phase allocation method is used.

In the first phase, the terminal sends the network part a ChannelRequest CR 600A. The terminal uses a specific training sequence toindicate to the base station that the resource request is specificallyof the EGPRS-type. After having received the message, the network partallocates to the terminal a specific number of channels on the radiopath for data transmission (step 602A) and informs the terminal aboutthe allocated resources by sending an AGCHPUA (Access Grant ChannelPacket Uplink Assignment) message 604. The message may also compriseinformation about the frequencies used in the cell and about thefrequency band with regard to which the base station first wishes toknown the terminal's characteristics. In addition, the network partallocates in phase 606A one or more radio blocks to the terminal forcontrol messages.

In the first control block the terminal sends a PRR (Packet ResourceRequest) message to the network part (step 610A). The message comprisesinformation about the terminal's radio path characteristics, preferablyrelating to the frequency band that was first requested in the AGCHPUAmessage. The PRR message also comprises information stating that theterminal has other characteristics than those given in the message.

In the next control block in step 612A the terminal sends a secondmessage ARAC (Additional Radio Access Capability) comprising informationabout the terminal's radio path characteristics, particularly withregard to all the frequency bands that are available in the network. Theterminal received this information in step 604A. As in the previousalternative, also in this case the transmission of the message isoptional.

If necessary the network allocates new resources in step 614A to theterminal on the basis of the information it has received.

In the next step 616A the terminal starts to send data to the networkpart using the radio resources allocated to it.

FIG. 7 a illustrates an example of signalling according to a preferredembodiment of the invention. At first the terminal sends the networkpart a channel request CR (Packet Channel Request) 700. After havingreceived the message, the network allocates to the terminal a channel onthe radio path for data transmission and sends information about theallocated resources to the terminal in an AGCHPUA (Access Grant ChannelPacket Uplink Assignment) 702. The terminal then sends a first controlmessage PRR (Packet Resource Request) 704 which comprises informationabout the terminal's characteristics regarding the frequency banddefined in the AGCHPUA message of the base station. Next, the terminalsends a second control message ARAC (Additional Radio Access Capability)706 which comprises information about the terminal's characteristicsrelating to other frequency bands. This message is optional. After thecontrol messages, the terminal starts to send data to the base stationon one channel 708. If necessary, the network part allocates newresources to the terminal on the basis of the information it hasreceived, and informs the terminal accordingly in step 710 with a PUA(Packet Uplink Assignment) message. After having received this messagethe terminal can transmit to the base station on several channels withinthe limits of its characteristics and the resources allocated to it.

FIG. 7 b illustrates another example of signalling according to apreferred embodiment of the invention. First the terminal sends thenetwork part a Channel Request CR 714. After having received the messagethe network part allocates to the terminal a specific number of radioblocks on the radio path for transmission of control data, and informsthe terminal about the allocated resources in an AGCHPUA (Access GrantChannel Packet Uplink Assignment) 716. The terminal then sends a PRR(Packet Resource Request) message 718 to the network part. Next, theterminal sends a second message ARAC (Additional Radio AccessCapability) 720, which is an optional message. The network part receivesthe message, allocates additional resources, if necessary, and sends anacknowledgement (PUA message) 722. The terminal then starts datatransmission 724 to the network part using the radio resources allocatedto it.

An advantage of the two-phase allocation method of the inventioncompared with the prior art two-phase allocation method, which isillustrated in FIG. 1, is that the method of the invention allows moreinformation about the terminal to be sent, i.e., information about allfrequency bands supported by the network and the terminal. Previouslythe information was restricted to one frequency band alone.

Let us then examine an example of the structure of the ARAC messagecontaining information about the terminal's radio path characteristicsin the preferred EGPRS system: < Additional Radio Access Capability >::= < MESSAGE_TYPE : bit (6) > < Global TFI > :Global TFI IE) > < L | H< MS Radio Access Capability : MS Radio Access Capability IE>} < sparebits > ;

Global TFI is an information element (Temporary Flow Identifier) actingas a message identifier, i.e., it identifies the terminal a message isaddressed to. MS Radio Access Capability is an information elementcomprising the necessary information about the terminal's radio pathcharacteristics.

Let us then examine an example of the structure of the AGPHUA (AccessGrant Channel Packet Uplink Assignment) message sent by the network. <AGCH Packet Uplink Assignment > ::= < L2 PSEUDO LENGTH : bit (8) > <PROTOCOL DISCRIMINATOR : bit (4) > < SKIP INDICATOR : bit (4) > <MESSAGE TYPE : bit (8) > < Packet Request Reference : < Packet RequestReference IE > > { 0 < AGCH PUA Contents : < AGCH PUA contents struct >>-- Message not segmented | 10 < AGCH PUA part 1 contents : bit(134) > --Segmented, 1^(st) part | 11 < AGCH PUA part 2 contents : bit(*) > --Segmented, 2^(nd) part } < AGCH PUA contents struct > ::= { 00 --Message escape < PAGE_MODE : bit (2) > < Frequency Parameters : <Frequency Parameters IE >> < TIME_SLOT NUMBER : bit (3) > < TA_VALUE :bit (6) > { 0 | 1 < ALPHA : bit (4) } < GAMMA : bit (5) < AccessTechnologies Request : Access Technologies Request struct > { 0 < MultiBlock Allocation : < Multi Block Allocation struct > > | 1 < One PDCHAllocation : < One PDCH Allocation struct >> } < padding bits > ! <Message escape : { 01| 10 | 11 } bit (*) = <no string> > }};  - Extendedfor future changes

Access Technologies Request is a list used by the network for requestingthe terminal to send information about itself. The elements on the listare preferably frequency ranges, such as 900, 1800, 1900 MHz, etc. Theterminal sends information about its radio path characteristics relatingto all the frequencies it supports.

Although the invention is described above with reference to an exampleshown in the attached drawings, it is apparent that the invention is notrestricted to it, but may vary in many ways within the inventive ideadisclosed in the attached claims.

1. A terminal of a radio system relaying packet-switched traffic, thesystem comprising a network part, the terminal being configured to:inform the network part that the terminal intends to send data to thenetwork part; receive from the network part information about radioresources allocated to the terminal and a query regarding the terminal'sradio path characteristics on a specific frequency band supported by theterminal; send a first control message to inform the network part of theterminal's radio path characteristics, the message comprisinginformation on whether there are additional radio path characteristics;and send a second control message comprising information about theterminal's additional radio path characteristics.
 2. The terminal ofclaim 1, wherein the terminal starts to transmit data to the networkpart using the allocated radio resources after the terminal hasreceived, from the network part, the information about the allocatedradio resources.
 3. The terminal of claim 1, wherein the network partsimultaneously inquires about the terminal's characteristics when thenetwork part informs the terminal of the default amount of allocatedradio resources.
 4. The terminal of claim 1, wherein the informationabout the terminal's radio path characteristics comprises informationabout the frequency ranges supported by the terminal.
 5. The terminal ofclaim 1, wherein the information about the terminal's radio pathcharacteristics comprises information about the terminal's capability tocommunicate using a plurality of time slots.
 6. The terminal of claim 1,where in the network part inquires about the terminal's characteristicson a specific frequency band when informing the default amount ofallocated resources to the terminal.
 7. The terminal of claim 6, wherein the first control message comprises information about the terminal'sradio path characteristics relating to the frequency band the networkpart first inquired about in the control message the terminal sent. 8.The terminal of claim 7, wherein the second control message comprisesinformation about the terminal's radio path characteristics relating toall other frequency bands used in the network other than the specificfrequency band.
 9. The terminal of claim 1, wherein if all theterminal's radio path characteristics have been relayed in the firstcontrol message, then data is sent in place of the second controlmessage.
 10. The terminal of claim 1, wherein when the terminal informsthe network part that the terminal intends to transmit data to thenetwork part, the terminal uses a training sequence to inform thenetwork part of the type of resources needed.
 11. A network part of aradio system relaying packet-switched traffic the network part beingconfigured to: receive from a terminal information indicating that theterminal intends to send data to the network part; allocate a defaultamount of radio resources to the terminal; reserve one or more radioblocks for the terminal's control messages; inform the terminal aboutradio resources allocated to the terminal and query the terminal aboutthe terminal's radio path characteristics on a specific frequency bandsupported by the terminal when informing the terminal about the defaultamount of allocated resources; receive a first control message from theterminal, the message comprising information about the terminal's radiopath characteristics and information on whether there are additionalradio path characteristics; and receive a second control message fromthe terminal, the message comprising information about the terminal'sadditional radio path characteristics.
 12. The network part of claim 11,wherein the network part is arranged to allocate radio resources to theterminal in accordance with the terminal's characteristics.
 13. Thenetwork part of claim 11, wherein the terminal is arranged to start datatransmission to the network part using the allocated radio resourcesafter receiving the information about the allocated resources from thenetwork part.
 14. The network part of claim 11, wherein the network partis arranged to inquire about the terminal's characteristics wheninforming the terminal about the default amount of allocated resources.15. The network part of claim 11, wherein the information about theterminal's radio path characteristics comprises information about thefrequency ranges supported by the terminal.
 16. The network part ofclaim 11, wherein the information about the terminal's radio pathcharacteristics comprises information about the terminal's ability tocommunicate using a plurality of time slots.
 17. The network part ofclaim 11, where in the network part inquires about the terminal'scharacteristics on a specific frequency band when informing the defaultamount of allocated resources to the terminal.
 18. The network part ofclaim 17, where in the first control message comprises information aboutthe terminal's radio path characteristics relating to the frequency bandthe network part first inquired about in the control message theterminal sent.
 19. The network part of claim 18, wherein the secondcontrol message comprises information about the terminal's radio pathcharacteristics relating to all other frequency bands used in thenetwork other than the specific frequency band.
 20. The network part ofclaim 11, wherein if all the terminal's radio path characteristics havebeen relayed in the first control message, then data is sent in place ofthe second control message.
 21. The network part of claim 11, whereinwhen the terminal informs the network part that the terminal intends totransmit data to the network part, the terminal uses a training sequenceto inform the network part of the type of resources needed.